Mosquitoes look for standing water to breed and lay their eggs -- a neglected and wet compost pile easily holds small puddles of water ripe with eggs and larvae. Water is not the only attraction for mosquitoes at the compost site. Mosquitoes rely on plant sugars, like nectar, for sustenance. As a result, any exposed plant material that is not mixed into the pile may be a food source, such as deadheaded blossoms. Contrary to popular belief, mosquitoes do not drink blood for energy -- blood is merely a protein source for egg production in females."